Cooler South Atlantic causes malaria rise in India

The Times of India , Tuesday, March 05, 2013
Correspondent : Subodh Varma
NEW DELHI: Everybody knows that the world is interconnected, but this takes the cake: colder than normal sea temperature in the tropical South Atlantic appears to cause malaria epidemics thousands of kilometers away, in North-Western India.

Led by ecologist Mercedes Pascual of the University of Michigan, US, an international team of scientists including RC Dhiman from New Delhi based National Institute of Malaria Research (NIMR) found that lower sea surface temperatures in July in the tropical South Atlantic, west of Africa, were correlated with more rainfall over Kutch and Rajasthan in the monsoon. When the rainfall crossed a certain threshold, enough water was available for the malaria carrying Anopheles mosquito to breed. This in turn led to increased incidence of malaria in the following October and November.

"For this region of India and for this window of time in recent decades, the tropical South Atlantic appears to play a dominant role on rainfall and, through rainfall, on malaria," Pascual said, in a statement by the University of Michigan at Ann Arbor..

In a retrospective analysis of malaria epidemics in the region between 1985 and 2006, the researchers found that July sea surface temperatures correctly anticipated nine out of 11 epidemic years and 12 out of 15 non-epidemic years.

The study has been published in the journal Nature Climate Change.

Since there is a four month gap between the colder temperature event and the onset of malarial epidemic, the study indicates that it can be used as a new forecasting tool should improve public health in the region. Planning for indoor insecticide spraying, one widely used control measure, could benefit from the additional lead time, for example.

"The climate link we have uncovered can be used as an indicator of malaria risk," Pascual said. "On the practical side, we hope these findings can be used as part of an early warning system."

After being nearly eradicated in India, malaria re-emerged there in the 1970s. An estimated 9 million malaria cases occur in India annually.

The team analyzed epidemiological records of malaria incidence in northwest India and used statistical and computer climate models to test potential links between sea surface temperatures, monsoon rains in northwest India, and malaria epidemics there.

They found that most malaria epidemics in northwest India, which peak in October or November, occur when rainfall in the preceding summer monsoon season equals or exceeds a rainfall threshold presumably required to support the growth of Anopheles mosquitoes.

 
SOURCE : http://timesofindia.indiatimes.com/home/science/Cooler-South-Atlantic-causes-malaria-rise-in-India/articleshow/18811016.cms
 


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